Disclaimer: Characters (apart from the occasional Comrade) belong to JK Rowling and Warner.

ooOOoo

Chapter 73: Wavy Line, Eye, 100C

The last of the light had gone from Luna. Without protest, she disappeared into the castle, silently sinking into the darkness within, leaving Harry and Draco in the sunbathed courtyard with Simon.

Harry and Draco squeezed Simon through a small door in the wall (barely big enough for the horse to fit through), down a few shallow steps and over a stone bridge (Simon blinked at the bridge sleepily – Harry sensed the horse would have balked at it normally, but on the downside of his psychedelic journey he followed Harry and Draco as meekly as Mary's Little Lamb) and back up to the paddock. Harry shook his head at Remus, who was hovering in the ivy-shadowed doorway at the base of a tower. Luckily Simon didn't notice the werewolf, or there could have been further excitement. The horse was a little dazed and kept yawning and blinking blearily, which could have been why he didn't react to Remus.

As soon as it was back in the paddock, the horse stretched out on the ground with a groan of pleasure and went to sleep.

There was no point in going to class now. Harry and Draco stayed sitting on the grass by Simon a few minutes longer, each worried the horse had been damaged by the gallop through the sky. Harry, still shaken from his ride, decided it was better to talk than think about what had just happened, even if he was talking about something threatening. He took the opportunity to once again ask Draco about the barrier. Draco's earlier description of the barrier turning him into jelly had given Harry the mental picture of a blancmange in Slytherin robes, and Harry had a personal horror of being immobilised. It made him claustrophobic just thinking about it. "You really couldn't move?"

"Well… maybe I was too scared to try. But it was like having everything seize up either way – terror or the spell, it was the same effect. But then it was over," he added, perhaps correctly interpreting Harry's frown. "And when you're through, the worst really is over."

"It wasn't for Simon. He could sense the Dementors…"

"Luckily for me."

Harry didn't really have anything to say to that. He picked a stalk of grass and leaned up against Simon's back next to Draco, wondering what they'd do if the horse had been badly affected by his latest adventure. He was going to ask Draco's opinion on that when Simon began to snore. Draco shook his head and sighed, reaching back and rubbing the horse's round belly. "Just another day at Hogwarts for him."

Harry nodded and pressed the heels of his hands against his eyes, which felt grainy, for a second. "And for me."

Draco gave him a sideways look. "But the attempt on someone's life wasn't aimed directly at you."

A bit slow from tiredness, Harry realised it was a joke. A Malfoy joke. "That's true. D'you think I should be taking that personally?"

Draco grinned. "I would." He stood and began to walk down the hill. "Come on. There's a werewolf to appease and I have to withdraw my candidacy. And explain why I've missed History."

Harry had missed History, too. He was lucky he hadn't become history. Or hit the ground hard enough to become geology. "What? You don't want to run for Comrade President anymore? What brought this on?" he asked as they closed the gate behind them.

Draco gave a lopsided shrug, left shoulder then right. "Things to do, people to see, Dark Lords to remove from the dimension we call life…"

Harry shrugged to himself. It was likely Draco would have changed his mind again by dinner, but he didn't think it would help if he pointed this out.

They walked on towards the castle, the only sounds the swish of their shoes through the grass and the occasional crackle as Draco used dandelions for target practice. It wasn't hard to surmise he wasn't as blasé about quitting the political race as his words suggested: the magic behind the hexes crisping the dandelions was tight with some bottled-up emotion.

"You know," Harry ventured, after some thought, "if you withdraw now, people might start asking questions."

"People… like headmasters and nosy werewolves, you mean?"

"Those sorts of people, yes."

"Hum. Hadn't thought of that." He seemed to perk up. "Guess I'd better pencil in campaigning around making potions and everything else… Might ask Trudi to dig out that sandwich board she was wearing last week when I was quarantined in the Infirmary and do a little bit of last minute campaigning for me."

"Give her a bell to ring, too." Harry liked the image.

Apparently so did Draco. He laughed. "I can just picture her sneaking up behind people and going crazy with a giant bell. 'Oyez, oyez!' Have you seen those goblins in Diagon Alley advertising Gringotts mortgages? Put a Sonorous charm on the bell – really put the 'pain' in 'campaigning'."

Harry was also chuckling. "She's really getting over that whole shyness issue."

"She is, isn't she. In fact, she's – ah. Our unwelcoming committee."

The unwelcoming committee was Lupin and Flitwick, walking towards them with the sort of neutral expression on their faces which meant something nasty was brewing and if there wasn't a sodding great barrier between Hogwarts and the rest of the world preventing it, expulsion might have been on the cards.

"Is there any possible sane answer you two idi- lads can give us about why Harry was out riding a horse on the roof?" Remus asked mildly. A muscle jumped in the corner of his jaw.

"Luna," Draco and Harry replied as one.

"Honestly, it wasn't his fault," said Draco. "Potter just got… caught up in things..."

"Malfoy tried to stop her…" Harry was saying at the same time.

Remus and Flitwick exchanged glances, probably at the astonishing fact that Draco Malfoy and Harry Potter had just defended each other rather than themselves from each other.

"Luna? Oh dear. I should have guessed given all the trouble she's been in lately," Flitwick sighed. "Well. There's an emergency meeting in Professor Dumbledore's office. You two really need to be there."

"And Luna?" asked Harry.

"I saw her inside and reminded her she had already been given tasks to do in the Library – that's whenever she's not in class," Flitwick returned sternly. "Even if she'd had nothing to do with putting a horse on the roof, she would have had nothing more to do with the, shall we say, current project."

"Oh." Harry wasn't sure how he felt about that. On the one hand, Luna had nearly killed him. But now she was ejected from the secret plans to save Hogwarts there was no hope she'd ever be Harry's girlfriend again. It tweaked that raw place deep in his chest. "So… now?"

"Right now," said Remus. "Best time for it seeing as how you two have such a casual attitude towards attending classes." He and Flitwick looked just as tired as Harry felt – Harry reminded himself that he wasn't the only one who'd been woken up early. At least he hadn't had to clean up after the explosion.

In the Headmaster's Office, Harry was pleased if surprised to see Ron and Hermione there as well as Sirius, Dumbledore and McGonagall.

McGonagall gave him and Draco a nod without any real warmth to it, although that was generally her way. Sirius was studying one of Dumbledore's little metal objects, which was spinning in his hand with an incongruously deep if faint chugging sound, like bubbles coming up through a long pipe full of water. He put it on the shelf by Fawkes and rubbed his hands together with a suggestion of unease, although it could have been to remove dust.

Ron and Hermione put cups to saucers and gave Harry identical worried looks. Harry was tired enough to have the question of their being possessed by Fred and George flit through his brain.

"As Miss Granger and Mr Weasley already know more about your plans than probably any of the adults in this room, including myself," Dumbledore began without preamble, "I thought it best if we include them."

"Er…" said Harry. His stomach had just plummeted into his sneakers and appeared to have taken his power of speech with it.

Hermione shrugged, but whatever she might have said was forestalled by Dumbledore waving his hand towards four chairs, which trotted forward and bumped into the backs of the knees of those standing, giving the strongest hint they were meant to sit down.

Harry, Draco, Lupin and Flitwick sat, the two boys slightly gingerly; Harry suspected Draco had the same uh-oh feeling of trouble boiling over the horizon as he did, although the Slytherin's face held only the politest of innocent interest.

Dumbledore would have learned to see through that one two or three generations of Malfoys ago.

"I was wondering if you two could enlighten me further on a certain potion you were working on? To be specific, one that could break the barrier."

Harry, Draco, Hermione and Ron exchanged a quick set of eye-contact; Hermione and Ron looked just as surprised by this as Harry felt, which suggested they hadn't told Dumbledore, which suggested…

Sirius cleared his throat as Harry turned to him, and raised a finger to forestall anything Harry might have said. "It's necessary to give full information to the headmaster, Harry. I wish there was the time for you to approach him in your own time, but tomorrow night the barrier must come down or not at all. It's time for us to all lay our cards on the table."

The room swayed as Harry took it in. He couldn't believe it. Sirius had betrayed him. And Harry, trusting Sirius, had betrayed his friends. His face burned. He couldn't look at anyone else in the room.

"I trusted the four of you in the orchestration of the plan to neutralise Voldemort," Dumbledore was saying, "because I expected you to involve me at any stage should there be a need for my assistance. I find it a great pity you felt you could not confide in me anything concerning this second potion – a potion for breaking the barrier." Harry wilted under the force of his disappointment. Even Draco, though he affected to be immune, couldn't hide the fact that the words had gone more than skin deep for him, too. "But," continued Dumbledore, "although I would have preferred for you four to come to me in your own manner, as Sirius has pointed out we have not the time to waste with waiting. Nor with mistrust."

Harry looked up and into Dumbledore's blue eyes, which were fixed on his and conveying the almost palpable regret that Harry had been unable to let him in on the full nature of the potions work he and his friends had been up to. Guilt, because he wasn't sure if he deserved to feel guilty, only made Harry all the angrier.

"We don't know if it'll work or not," Draco pointed out after flicking a glance at Harry that might have contained sympathy. Or not.

"Nonetheless, you could have brought in one or two professors for extra help," McGonagall pointed out. "It would certainly have made success more likely."

Remus cleared his throat, distracting Harry from his own rising anger that McGonagall should be a part of this – this attack. "Headmaster, professors…" he began. "I must admit to, er, provoking this secrecy."

Sirius raised an eyebrow, as did Dumbledore. Flitwick blinked rapidly.

"What in the world do you mean, Remus?" asked McGonagall.

Remus sighed softly. "I mean that Miss Granger came to me a while ago and I believe my words to her were, to be precise, to 'leave well enough alone'."

Dumbledore raised an eyebrow at Hermione, who shrugged minutely. "I see," he said. "Brandy on a shabby phoenix, as they say."

"And then Harry thought Remus was turning into Snape," said Sirius, perhaps trying to lighten the heavy atmosphere.

He didn't succeed.

"What?" said Lupin, shooting Harry an alarmed look. "What, seriously?"

Harry rubbed at his eyes, which were definitely grainy. There was a headache coming, too. "Well… Not literally. I didn't mean you were possessed or anything. Just filling a certain space at Hogwarts."

"Really." Lupin still looked less than pleased. "Well. Thank you for what could be construed in a dim light as constructive criticism. I'll certainly take that under consideration." Harry took that to mean that Remus was a long way below pleased. Several fathoms, at least, and in range of the sorts of fish which lured prey with lights. "In the meantime, if you would permit me to step outside that certain space for a few moments," he said acidly, which only made him seem more Snape-like, "I'd like to defend you lot to the headmaster by saying that myself and other staff members were approached and rebuffed – unwisely, as it turned out – the offers of help from certain student groups, and it was my mistake not to give you the attention you deserved."

"Did you get those fourth year Ravenclaw girls coming to you to see about putting a spell on Hogwarts that would keep everyone asleep until Merlin's Heir came and kissed the one he would choose as his wife?" asked McGonagall, who seemed to be sympathetic to Lupin.

Remus gave her a wry if tired smile. "No. Thank Circe. I suppose one of them was supposed to be the love interest."

"They didn't say. But I wouldn't put money against it."

"Oh, they came to see me," Flitwick squeaked. "My goodness… we've had fairy tales coming out of the woodwork since the barrier went up. Potter, didn't you ask me about…?" He trailed off. Flitwick wasn't an idiot. "Or should I ask, did you ever find the Golden Sickle?"

"He did," Dumbledore said. "Long story." He spread his hands over his desk. "One that may or may not have bearing on the situation at hand, so I shall tell you about it later, Filius. Oh dear. Well, Remus, thank you for telling us. It certainly makes the secrecy more understandable." For a moment Dumbledore looked almost as tired as Lupin. "Please – will you trust us now?" he said to the students. "Is there anything else you can tell us? Anything you have been holding back? Because the way things stand, the slightest piece of information could be vital."

Harry didn't mean to glance at Draco, but Dumbledore caught the look.

"Harry? Draco?"

Draco's brow creased. "Er… I'm running for President of Slytherin. I'm not sure how that would affect anything to do with the barrier…"

"And I wouldn't dare interfere with Slytherin politics," Dumbledore said. He leaned back a fraction and there was the hint of a smile under the white beard. "I wish you the best of luck with your campaign."

"So you weren't going to tell me to stop running?" Draco tilted his head. "To be honest, I was wondering if I should. Elections are the day after tomorrow and – well – either the barrier will be down and the elections will be moot, or… Um."

Dumbledore nodded slowly. "Thank you for the concern. But would it not prove disruptive if you suddenly withdrew from the electoral race? I was thinking in terms of everyone at Hogwarts getting suspicious that something strange was up…"

Draco was nodding, too. "Mm. That's what I thought. So Potter and I thought it would be best to see how much time I need to spend on the potions… Granger had already argued convincingly for telling you about the barrier potion as you were going in the direction of the anchoring trees outside the barrier anyway, so Potter and I were going to check with you and Professor Flitwick about what exact input of time was necessary from us… We are capable of thought process rather than the knee-jerk reactions you seem to be accusing us of," he finished with a chilly but dignified glare in McGonagall's direction.

Harry kept his face impassive. Draco had said a mouthful, and if Dumbledore had any mindreading abilities he'd see it as the farrago of lies it was. As farragoes of lies went, this one was a beauty. Harry was particularly impressed by how Draco had woven Hermione into it, and although the way he'd put the professors into the wrong wasn't subtle enough to stop McGonagall from pinching her nostrils, Harry thought it a nice touch.

"I'm glad to hear it," said Dumbledore as Fawkes woke and began to preen. "And I apologise for any slur against your intelligence – collective and individual. If I thought you incapable of wisdom, let alone rationality, I would not be calling you here for your input into a delicate situation, rather I would be taking the information you had already collected and sequestering it for the sole contemplation of myself and select members of staff."

Draco gave a jerky nod in acknowledgement.

"Your help is needed. It is necessary. And, as has been pointed out by Sirius, we need to all be open with each other. I cannot demand such a thing. I can only ask, for the benefit of Hogwarts. Will you four help, each giving the whole of your intellect and heart and spirit?"

Hermione's soft cough broke the silence. "Of course, sir."

Ron and Harry nodded. After a moment that might have been calculated for effect, so did Draco.

Dumbledore lowered his eyes to the desk. "Thank you," he said softly.

Harry felt a stab of guilt. Should he admit what he and Draco were planning?

Sirius' hoarse voice said, "Maybe we can solve that problem with the anti-Voldie potion now all of us are working together," and although it was meant as a peace offering it only irritated Harry, and Harry pushed the impulse to confess away.

"Correct," said Dumbledore. "But first I would like to inform Miss Granger and Mr Weasley about certain aspects of Hogwarts' problem with wards they may not know about, unless…?" He glanced at Harry.

Harry shook his head. No, he hadn't told Hermione and Ron about the wards coming under threat.

"Hmm. Well, as they already know about both potions and Hufflepuff's Sickle, I suppose we should give them the last piece of the puzzle – or what little of the puzzle we have. To summarise: the wards are dissolving and Hogwarts is in danger of collapse."

Hermione gasped and Ron had gone very pale around his freckles.

Dumbledore nodded tiredly. "I wish I had good news for you, children, but perhaps you can make it for yourselves and the rest of us. Remus? You were testing out some of your calibration charms earlier. Do you have anything to add about the wards?"

Remus sighed and stretched out his legs, looking down at the worn leather toes of his shoes, reminding Harry strongly of the time in this office he had told Harry and Draco about the wards crumbling. Harry thought again how much the werewolf had aged in the last few months – surely it hadn't all been from the worry over Wolfsbane potion? "I wish I had better news, Albus," he said softly. "But I found a sub-hex under Falstaff's Unlocking Constant – that's the ward flux destabilising spell I'm now sure You-Know-Who is using. That sub-hex acts to speed up the natural decay of the wards while blocking the stone-bed regeneration set up by the Founders.

"Can't you try inverting it with a Platonic Universal?" asked Hermione, her face pale. "Or one of the Mild Over Matter classes of protection charms?"

Remus smiled sadly. "Unfortunately, no. I would need to cast all of those on the locus of the decay."

"And getting to You-Know-Who is difficult at the best of times without a nasty fat barrier between you and him," sighed Hermione.

Remus nodded. "I'm sorry I didn't involve you earlier, Hermione."

She gave a one-shoulder shrug. "I didn't help."

"Not yet. But give you another thirty seconds and I'm sure you'll come up with some fresh ideas." His eyes crinkled at the corners – this time the smile had reached them. Then the warmth faded. "I'm afraid that after factoring in the sub-hex, my best projections give us about seven more weeks before the damage becomes irreparable."

"Er… only seven weeks?" asked Ron, who was still looking puzzled from the brief exchange between Hermione and Lupin.

"This is the biggest secret Hogwarts currently holds," Dumbledore said gravely. His lined face was sad. "All of you must keep this totally secret."

"Should you really be telling us?" Ron said.

Draco glared. "What – wait until the Slytherin is out of the room?"

"No," said Ron evenly, "I merely wanted to raise the concern that it's a large responsibility. I don't see many teachers in here – I would have expected Professor Sprout at the least."

McGonagall nodded, as if pleased Ron had said this. Harry was busy wondering when Ron had suddenly grown so mature, and did he, Harry, look childish by comparison? He was probably being childish just wondering if he was… and his head really was beginning to ache…

"She already knows," Dumbledore said, ignoring his deputy head. "As do the rest of the staff. Er… barring Professor Trelawney and Mr Filch. Other than them, it is only those in this room who know… or who are to be informed."

"I notice Potter and I are here, so I'm guessing Simon may crop up in conversation – should Luna be included?" Draco asked, although he must know damned well that Luna was currently persona non grata. Harry wondered what he was aiming at.

Dumbledore steepled his fingers and said carefully, "Her behaviour has been erratic of late. Much as I would like to involve her, I wouldn't like to incorporate such a random factor, if such she can be termed, into an already delicate situation."

Draco nodded, agreeing.

Harry looked down. He couldn't argue with that. Luna's recent record – turning herself green, sending Simon bobbing up into the air with Harry on his back, Sirius' riding lesson, the explosion in Snape's personal laboratory… not to mention the temper-explosion after Colin had taken photos of Simon again – her record wasn't reassuring.

"Sirius has been helping me monitor the wards," said Remus. "He's also the one who's been lobbying for you four to be included," he added, as if anxious that Harry not be too angry with Sirius.

Fat chance.

"'Four'?" said Draco with leaden scepticism.

"'Four'," said Sirius firmly. "Your involvement in this is vital, Draco." But he didn't look at Harry.

Draco's eyebrow twitched as if he was undecided on whether he should be pleased by the ego-stroking or annoyed by the familiarity. Before he could decide on the latter, Sirius continued: "There is a line of information that the Dark Lord is going to attack Hogsmeade tomorrow night."

"From what source?" asked McGonagall.

"Er…"

If Sirius named names Harry was going to… Harry didn't have the faintest idea what he'd do to Sirius.

Help came from an unlikely source.

"From my mother," Draco said bravely. "And if any of this gets out I'll know to track it back to someone who was in this very room." Nobody told him not to be silly – even Ron must have sensed that this wasn't the usual Malfoy bluster. Blood feuds had been set in motion by calmly-spoken young men often enough in Wizarding history. "She's also the one who sent the notes –" he flicked a hand at the desk, where a sheaf of parchments lay "– for the anti-Voldie potion."

"Did she develop the potion herself?" McGonagall asked, politeness barely masking her doubt. "Only I don't remember her being that interested in Potions. More of an Arithmancy buff, if I remember correctly. Oh, and one of the best Chasers Slytherin ever fielded. Luckily for Gryffindor she only kept it up for a couple of years…"

"Probably broke a nail," Draco said with a wry smile.

McGonagall gave him a look more fond. "Aye, that was it. But would she have been able to come up with a potion of such complexity?"

"Arithmancy would have helped set the parameters… but no, she was working with Professor Snape to develop the potion."

"Ah." McGonagall and Flitwick both looked more confident, as did Lupin and (to what would undoubtedly be his future shame) Sirius.

"When exactly did she do work on this?" Flitwick asked.

"She didn't pinpoint a date. Anywhere from a few days to three years before Harry semi-bumped him off," Draco replied, so smoothly perhaps only Harry (and probably Dumbledore) knew he was lying. "She'd kind of gone off him after, well… meeting him, I should imagine."

As everyone in the room was keen to keep the peace for the time being, no-one asked where Lucius had been during all of this.

"So do you trust the source of the information, Albus?" McGonagall asked. "No offence, Malfoy, but you are risking Filius as well as yourself, and –"

"– And while Narcissa Malfoy would not risk a hair on her son's head, a certain third party antagonistic to ours and with little regard to life, even if it is a Slytherin's life, might have intercepted this message and twisted it to make a trap," Dumbledore finished for her before Draco could take offence, even if such was not meant. "Hogwarts is under threat and I am the headmaster: that is why the risk must be taken by myself."

"And I choose to go," Flitwick put in. "Dangerous as it looks, sooner or later it is a threat I must face. If I stay I may die – is it not better to fight to stop the threat now?"

"Not necessarily, Filius. And, Albus, your argument doesn't follow logical premises, Albus," McGonagall countered crossly. "If Aurors can't stop them, what makes you two idiots think you have a chance?"

"Because we are the best warriors Hogwarts has to send," Dumbledore said, his voice firm. He lifted a hand to stop her arguing further. "And if we fail, then I can be satisfied that I leave behind me a capable headmistress in your person."

She sighed. "Albus…"

"Please. I have a few surprises up my sleeves."

"And they are?"

"If I told you they wouldn't be surprises." For the first time that morning, his blue eyes twinkled.

ooOOoo

Rather than provoke McGonagall into an argument, it was decided to examine the notes on the potions. Hermione had the barrier-breaking potion recipe handy (it was in the potions book from the library which she'd taken to carrying around with her) and McGonagall and Lupin as well as Dumbledore were interested in Snape's solution to overcoming a temporal barrier.

"Severus Snape wrote in a library book?" was, predictably, McGonagall's first reaction – she'd said it as Lupin was opening his mouth, so he must have been about to say the exact same thing, Harry guessed.

Dumbledore was thumbing through the pages. "It makes sense," he said eventually. "Rather an unconventional use of spring snow mistletoe, but when you take into account the triumvirate of oaks… Yes."

After a short discussion on the possible limits of the barrier-breaking potion, they spread the notes for the anti-Voldie potion out on the desk and Hermione began to explain what they had done and how they'd reasoned their way through some of the more obscure parts of the original notes Narcissa had sent them. Harry liked the way she said 'we' – it made it sound like a group effort rather than the true story of Hermione leaping up and shouting the Potions equivalent of "Eureka!" periodically.

But they were still stumped on the wavy line, eye, 100C.

Hermione went into a lengthy discussion with Dumbledore and Lupin (everyone else threw up their metaphorical hands in surrender) over the possibilities. Harry began to wonder if anyone had really given proper weight to the potential for –

"Harry?"

"Hm? Oh. Sorry. Just thinking about, um, the potion. It just keeps getting more and more complicated. And you had a point about not keeping secrets, sir," he said to Dumbledore, ignoring the fact that Sirius was the one who'd initially outed them. "We need to get in someone who really knows about potions. This is too important not to fully exploit all Hogwarts' resources."

"Do you mean another student, Harry?" Flitwick said, a brief spasm of worry flickering over his face.

"Yes, sir. There's a Slytherin student who –"

"Hmm. I think I know who you mean. Well, at least he wasn't the one who woke everyone up this morning…"

"No, just nearly brought down the castle the other day," Remus said dryly. McGonagall sighed, and Sirius looked queasy. Remus rubbed the side of his nose in a pained way, and added, "Shall I fetch Elmsworthy, Headmaster?"

Dumbledore nodded. "We live in dire times, Remus. Yes, fetch Elmsworthy."

ooOOoo

"Similia similibus curentur. Like cures like." Elmsworthy was perched on a chair next to Dumbledore's desk, peering over Harry's shoulder at the notes lying on the desk, his expression finally thawing as he realised something interesting had come his way.

They'd had to drag him out of a Potions class. Not a seventh-year class – he had been roped in to teach the first-years and had complained bitterly to Harry, who'd been sent with Draco to get him. The first-years were unappreciative also – they had been having a great time making a potion that allowed them to throw their voices. "I finally get the chance to show the little buggers the real side of Potions – how fun they can be – and you two morons come along!" he snarled.

"Since when was Potions fun?" Harry countered. "I mean, first year Potions? That was the pits. Almost as bad a second year Potions…"

"Oh, I don't know," said Draco. "I was hooked right from the whole 'bottle glory and put a stopper in death' thing."

"Huh," said Harry, who had a very different perspective on his first Potions class.

"I say, was Snape still using that speech on your year?" Elmsworthy said. "Yeah, I know it sounded impressive, but if he'd just pointed out how jolly interesting Potions as a subject is, he'd have made more converts. I tried telling him once –"

"'Converts'?" Harry and Draco had exclaimed. They had looked at each other. "You know… I don't think Snape was the sort of teacher to, er, push the frivolous side of anything," Harry said cautiously, wondering if there really was inter-dimensional travel and Elmsworthy had come from the parallel universe where Professor Snape was a happy-go-lucky educator who gave out lollipops to all students, Gryffindors included.

Elmsworthy had shrugged, his mournful face still glum at being torn away from his class. "Brewing is the most fun anyone can have. I don't know how I'd cheer myself up without it. I finally get the chance to teach a bunch of students the joy of it when you two show up…" he moaned.

Now, back in Dumbledore's office on the other side of Harry, Draco with his arms folded in silent protest looked very disapproving. He was still twitchy about the notes, but, Harry considered, he couldn't really be blamed for such an attitude given it was his mother's neck on the line. Draco's neck, too, if someone worked out it was his handwriting and hinted as much in the Dark Lord's ear; Draco was also the only one able to decipher the Briar code used on the scroll sent by his mother. "There." Elmsworthy poked a stained finger at the page. "See? It's using the vitalist argument. Professor Snape'd been working on it off and on for years, trying to see if a Muggle hypothesis from a Nineteenth Century physician was a legitimate extension of Paracelsus' theories of vitalism. Paracelsus, being a wizard with strong Muggle leanings, is quite fascinating and his Wizarding works had a lot to say on the subject of the 'elan vital' – what some call the soul while others maintain it to refers to chi or prana – and how it interacts with the physical form. The trouble is that the Wizard model of medicine – you know, Developed Galenism…"

No, Harry didn't know. Neither did anyone else other than Dumbledore and Hermione, judging by the blank expressions. But Harry's heart was already beginning to beat stronger with hope, and for the first time in a long time there seemed to be a light at the end of the tunnel – a light that wasn't the oncoming Hogwarts Express.

"…Er, it's the four humours?"

More blank looks. Although Dumbledore and Hermione were nodding slowly, as if anticipating what the Slytherin was about to say next.

"Is that like something Fred and George would use in their tricks?" Ron ventured. He'd scowled at the addition of Comrade Tyrol and moved his chair a tad closer to Hermione's.

Everyone ignored him, for which he appeared grateful. Ron slouched back in his chair and picked up his cup of tea.

"Pretend for one second none of us have the faintest idea of medieval medicine, other than a strong desire to avoid healers prescribing leeches," drawled Draco, who was, like Harry, fed-up with all the jargon thrown around the room in the last twenty minutes. "Well, apart from Granger who's probably researched it all in first year and the headmaster, who probably lived through it."

Remus shot him a stern look for his cheek, but Dumbledore's beard twitched, suggesting a smile that didn't quite break free, and Hermione seemed to have taken it as a compliment.

"Your loss," said Elmsworthy. "Never mind the long explanation, then. It's interesting you have a potion for this, because it seems to be counterbalancing the Galenic use of…" He looked up. "You know, if I was dumb enough to want to live forever, I'd use underlying Galenic principles for longevity (minus the bloodletting, of course because we're way past the take-two-leeches-and-see-me-in-the-morning school of medicine, what?), and combine it with – has anyone ever heard of the Vivicus Charm…? Never mind – it's not exactly on the curriculum. Besides, who in their right mind would want to live forever?"

"Me," Draco said instantly, although his expression was particularly brittle and his eyes snapped at the mention of the Vivicus Charm.

"Then you're a fool. The brightest part of life is its impermanence and the implication that there are other realms to explore beyond it."

"Lucky me," drawled Harry. "I'll be fortunate to make twenty-one."

He'd meant to lighten the atmosphere, but it came out gloomier than he'd intended. Ron looked down and kicked at the edge of the rug. Dumbledore's expression suggested someone had just kicked his favourite puppy.

"Only a maniac would want to be immortal," insisted Elmsworthy, studying the formula with a frown and ignoring the by-play.

No-one seemed to want to question him at the moment; Draco was staring up at the ceiling and Harry was just hoping Elmsworthy wouldn't figure out why they wanted to make the potion.

Hope failed him. The bitch.

Elmsworthy ran his fingers through his mop of spiky brown hair. "I can think of only one person who wants to be immortal and shows the signs of having gone about it in this fashion. I'm sure you know You-Know-Whom I'm talking about. So you're cooking up something to give our friendly neighbourhood megalomaniac a kick in his wanna-be-immortal goolies?" A line drew between his eyes. He looked up. "You're joking. Right?" He put his head to the side. "How in Merlin's name do you expect to get close enough to apply it? A potion like this" (he jabbed at the parchment) "needs an aqueous interface with the subject for activation."

"What?"

"You need to make him drink it. Or suck it up his nose – there's enough water in the sinus cavity to work, same with the lungs. But it wouldn't work with skin contact, not unless he was a frog. Even a suppository would –"

"All right, all right, all right," Harry said quickly, horrified at the mental images Elmsworthy was conjuring without a wand.

Sirius was frowning fit to crack a mirror. "Never you mind what the potion is for. Can you answer the question about the 100C?"

Elmsworthy gave him a look Harry couldn't even guess at. Sirius shifted slightly under it. "You're a Pureblood, aren't you?" said Elmsworthy.

Sirius took on a dangerous look. "I don't follow that Pureblood mania rubbish. What do you think I am – a Malfoy?"

Draco didn't react other than a slight twitch to the corner of his eye, although even Ron gave Sirius a stern look.

"I think you're a Black, Black. Y'know – cousin to noted psychopath Bellatrix Lestrange. And that wasn't my point." Elmsworthy smiled coldly, and Harry suddenly realised that Comrade Tyrol had something against Sirius. What, though? "My father went to school with you," Elmsworthy said.

Oh. Harry hadn't remembered any Elmsworthys back then.

Sirius grimaced briefly. He did, it would seem.

Elmsworthy tilted his head. "Ah. So you remember. He described you as being a typically narrow-minded twit, like most wizard-borns, and an object lesson to Slytherins." (Draco smiled, although he'd frowned at the crack at wizard-borns.) "Well, before you go on about Slytherin Purebloods, please keep in mind he married a Muggle, and that is possibly the only reason I'm able to tell you why Professor Snape wrote 100C in those notes. And because I actually went and asked Snape about stuff, I can tell you why there's a little wavy line and an eye."

He paused, the room silent, seemingly enjoying the attention.

"Pray enlighten us, Mr Elmsworthy," McGonagall sighed.

"It's based on the Muggle system of homoeopathy, where it is considered that a solution or substance containing the vital essence of the original disease-causing agent can cure the effects of the agent itself."

"That doesn't make sense," Draco argued. "Vitalism was discounted in the eighteenth century – Adelis the Ungainly did a series of experiments on Crups to work out their relative levels of phlogiston and calx, hoping to see if there was a magical quotient, and, well, let's just say the results were conclusive. Phlogiston was discredited. There's not an iota of magic involved, and according to Vector that's the only way the theory of vitalism could have worked."

Elmsworthy sneered. "Adelis was a moron. For starters he forgot to run proper controls in his experiments – all he used was a dozen Crups – not even a Jack Russell to see if there was a non-magical morphic factor." (Hermione mouthed later as Ron asked in a whisper who that Russell bloke was.) "And not only that, but he didn't use appropriate dampers to stop outside magical fluctuations influencing the magical vacuum he was trying to set up. He never proved anything. The theory of phlogiston and calx may exist on a level we haven't yet tapped into – I'm not saying it does, mind you, because I personally think it's a load of bollocks and vitalism, if it exists, exists without phlogiston or calx. But, like my hero Socrates, I'm open to the fact that no-one really knows anything. Except their own personal existence, of course. But I'm straying from the fact, the fact, Malfoy, that that sham of an experiment did not disprove vitalism."

"The point of it, please?" said Remus, the dip of his head making his words more polite than they might have otherwise been.

Elmsworthy scrubbed at his spiky brown hair. "I guess I'm just saying that Muggles and a few German fringe-wizards kept going with the theory, and developed it into a system of like curing like… providing you dilute the 'like' so massively it's usually not part of the cure any more."

"But does it work?" asked Hermione, who was still holding hands with Ron.

Harry wondered if she knew it made them look like guilty conspirators, and realised with that small pain in that locked-away part of him which still bled that it was lucky Luna wasn't sitting next to him with her hand in his, because otherwise he might have looked just as guilty.

It was unlikely Luna would ever hold hands with him again.

Harry shook his head at himself, angry at being distracted by… by… by things that were not meant to be his.

Elmsworthy launched into another lengthy explanation, ticking off items on his long stained fingers, his earnestness leaving him perched so close to the edge of his seat he was virtually squatting instead of sitting. Hermione like Dumbledore looked like she was running over old concepts, nodding at the points Elmsworthy made. His current expression not unlike McGonagall's, Draco looked a bit puzzled, but more annoyed than anything else at having his theories shot down by a fellow Slytherin. Elmsworthy mightn't make it in the diplomatic corps if he kept rubbing people's noses in their mistakes like that, Harry decided. Sirius was slowly drumming his fingers on the arm of his chair as if he knew there was a flaw in the argument somewhere but just couldn't put his finger on it. Remus was leaning back in his chair and his eyes were half closed, but Harry had no doubt he was listening intently.

Ron was blinking owlishly. Harry suspected he had a similar stunned expression. Apart from the way it looked like he was cracking the code, it had been a mistake to bring in Elmsworthy – it always ended up with Harry feeling like an idiot.

"I like your argument of Galenic overflow countering the egoistic repression of theories," Dumbledore said slowly, "although it has little practical bearing on the matter at hand, and also how like could possibly cure like, which seems highly pertinent and may even be the key, but how can we really be sure it will work?"

Elmsworthy shrugged. "Dunno. Mum uses some homoeopathics to supplement the usual doctor medicines and potions we get from Wizard healers. I was asking Snape about them at one point – he's got some remedies down in his lab. He wanted to test them out but didn't have time, and he was curious about Muggles using this brand of ur-magic. Said it was sort of a long-term backburner thing." He looked down at the notes again. "That's a hell of a backburner he had."

Dumbledore nodded. "I suspect he was too busy with everything else, such as teaching and countering Voldemort, to really give it the attention it deserved. Or we suspect, in retrospect, it deserved. Although to be fair stopping evil and educating the young is vital to our society."

"Eh." Comrade Tyrol shrugged away Snape's years of spying and teaching Potions as unimportant in the grand Potions-centric scheme of thing, and Harry realised that while Severus had been keen on Potions, he was now in the presence of a true fanatic. The fanatic was now saying, as if to set this impression in stone: "People really need to set their priorities carefully. Shame Snape spent more time on teaching and mucking about with politics instead of research. I always wondered why he stuck around Hogwarts, frankly."

"The smiling, happy faces of his students were his reward," Dumbledore said.

By the time the room stopped laughing (Sirius had to slap Remus on the back before he choked, Elmsworthy cracked a smile and even Draco and McGonagall were wiping away tears of mirth), Dobby had shown up with more tea and scones. That helped break the last of the tension.

ooOOoo